/*********************************************************************************
 *      Copyright:  (C) 2025 LingYun IoT System Studio
 *                  All rights reserved.
 *
 *       Filename:  socket_server_epoll.c
 *    Description:  This file 
 *                 
 *        Version:  1.0.0(20/03/25)
 *         Author:  Guo Wenxue <guowenxue@gmail.com>
 *      ChangeLog:  1, Release initial version on "20/03/25 17:15:13"
 *                 
 ********************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <ctype.h>
#include <time.h>
#include <pthread.h>
#include <getopt.h>
#include <libgen.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/epoll.h>
#include <sys/resource.h>

#define MAX_EVENTS			512
#define ARRAY_SIZE(x)		(sizeof(x)/sizeof(x[0]))

static inline void print_usage(char *progname);
int socket_server_init(char *listen_ip, int listen_port);
void set_socket_rlimit(void);

int main(int argc, char **argv)
{
	int						listenfd, connfd;
	int						serv_port = 0;
	int						daemon_run = 0;
	char			   	   *progname = NULL;
	int						opt;
	int						rv;
	int						i, j;
	int						found;
	char					buf[1024];

	int						epollfd;
	struct epoll_event		event;               //用于添加某个fd
	struct epoll_event		event_array[MAX_EVENTS];        //用于处理多个客户端
	int						events;              //多少个客户端发生了事件

	struct option			long_options[]=
	{
		{"daemon", no_argument, NULL, 'b'},
		{"port", required_argument, NULL, 'p'},
		{"help", no_argument, NULL, 'h'},
		{NULL, 0, NULL, 0}
	};

	progname = basename(argv[0]);
	  
	while((opt = getopt_long(argc, argv, "bp:h", long_options, NULL)) != -1)
	{
		switch(opt)
	    {
			case 'b':
				daemon_run = 1;
		        break;

	        case 'p':
				serv_port = atoi(optarg);
			    break;
																				   
		    case 'h':
		        print_usage(progname);
	            return EXIT_SUCCESS;

	        default:
	            break;
	    }
	}

	if(!serv_port)
	{
		print_usage(progname);
		return -1;
	}

	set_socket_rlimit();         //设置可为无数个客户端服务

	if((listenfd=socket_server_init(NULL, serv_port)) <0 )
	{
		printf("ERROR: %s server listen on port %d failure\n", argv[0], serv_port);
		return -2;
	}
	printf("%s server start to listen on port %d\n", argv[0], serv_port);


	if(daemon_run)
	{
		daemon(0, 0);
	}

	if((epollfd=epoll_create(MAX_EVENTS)) < 0)       //创建epollfd
	{
		printf("epoll_create() failure: %s\n", strerror(errno));
		return -3;
	}


	event.events = EPOLLIN|EPOLLET;   //EPOLLET事件触发
	event.data.fd = listenfd;         //存入listenfd

	if(epoll_ctl(epollfd, EPOLL_CTL_ADD, listenfd, &event) < 0)        //将epollfd添加进epoll_ctl
	{
		printf("epoll add listen socket failure: %s\n", strerror(errno));
		return -4;
	}


	for( ; ; )
	{
		events = epoll_wait(epollfd, event_array, MAX_EVENTS, -1);       //epoll等待fd
		if(events < 0)         //出错
		{
			printf("epoll failure: %s\n", strerror(errno));
			break;
		}
		else if(events == 0)          //超时
		{
			printf("epoll get timeout\n");
			continue;
		}

		for(i=0; i<events; i++)
		{
			if((event_array[i].events&EPOLLERR) || (event_array[i].events&EPOLLHUP))   //移除出错或者断连
			{
				printf("epoll_wait get error on fd[%d]: %s\n", event_array[i].data.fd, strerror(errno));
				epoll_ctl(epollfd, EPOLL_CTL_DEL, event_array[i].data.fd, NULL);
				close(event_array[i].data.fd);
			}

			if(event_array[i].data.fd == listenfd)     //如果是listenfd发生事件
			{
				if((connfd=accept(listenfd, (struct sockaddr *)NULL, NULL)) < 0)      //产生新的文件描述符connfd
				{
					printf("accept new client failure: %s\n", strerror(errno));
					continue;
				}

				event.data.fd = connfd;      //将connfd加入数组
				event.events = EPOLLIN;
				if(epoll_ctl(epollfd, EPOLL_CTL_ADD, connfd, &event) < 0)    //加入数组失败
				{
					printf("epoll add client socket failure: %s\n", strerror(errno));
					close(event_array[i].data.fd);
					continue;
				}
				printf("epoll add new client socket[%d] ok.\n", connfd);
			}
			else         //成功读到数据
			{
				 	memset(buf, 0, sizeof(buf));
				if((rv=read(event_array[i].data.fd, buf, sizeof(buf))) < 0)
				{
					printf("socket[%d] read failure or get disconnect and will be removed.\n", event_array[i].data.fd);
					epoll_ctl(epollfd, EPOLL_CTL_DEL, event_array[i].data.fd, NULL);
					close(event_array[i].data.fd);
					continue;
				}
				else
				{
					printf("socket[%d] read get %d bytes data\n", event_array[i].data.fd, rv);

				 printf("Read package from client: %s\n", buf);	
					
					
					/*  
					for(j=0; j<rv; j++)
						buf[j]=toupper(buf[j]);

					if(write(event_array[i].data.fd, buf, rv) < 0)
					{
						printf("socket[%d] write failure: %s\n", event_array[i].data.fd, strerror(errno));
						epoll_ctl(epollfd, EPOLL_CTL_DEL, event_array[i].data.fd, NULL);
						close(event_array[i].data.fd);
					}
					*/
					


				}
			}
		}     //for(i=0; i<rv; i++)
	}     //while(1)
CleanUp:
	close(listenfd);
	return 0;
}


static inline void print_usage(char *progname)
{
	printf("Usage: %s [OPTION]...\n", progname);

	printf("%s is a socket server progname, which used to verify client and echo back string from it\n", progname);
	printf("\nMandatory arguments to long options are mandatory for short options too:\n");

	printf(" -b[daemon] set program running on background\n");
	printf(" -p[port] Socket server port address\n");
	printf(" -h[help] Display this help information\n");


	printf("\nExample: %s -b -p 8900\n", progname);
	return ;
}


int socket_server_init(char *listen_ip, int listen_port)
{
	struct sockaddr_in		servaddr;
	int						rv = 0;
	int						on = 1;
	int						listenfd;

	if((listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
	{
		printf("Use socket() to creat a TCP socket failure: %s\n", strerror(errno));
		return -1;
	}

	setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));

	memset(&servaddr, 0, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_port = htons(listen_port);
	 
	if(!listen_ip)       //没传ip
	{
		servaddr.sin_addr.s_addr = htonl(INADDR_ANY);          //监听所有ip
	}
	else
	{
		if(inet_pton(AF_INET, listen_ip, &servaddr.sin_addr) <= 0)          //将ip转为4字节存入sin_addr
		{
			printf("inet_pton() set listen IP address failure.\n");
			rv = -2;
			goto CleanUp;
		}
	}

	if(bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0)
	{
		printf("Use bind() to bind the TCP socket failure: %s\n", strerror(errno));
		rv = -3;
		goto CleanUp;
	}

	if(listen(listenfd, 13) < 0)
	{
		printf("Use bind() to bind the TCP socket failure: %s\n", strerror(errno));
		rv = -4;
		goto CleanUp;
	}

CleanUp:
	if(rv<0)
		close(listenfd);
	else
		rv = listenfd;

	return rv;
}


void set_socket_rlimit(void)
{
	struct rlimit limit = {0};

	getrlimit(RLIMIT_NOFILE, &limit);
	limit.rlim_cur = limit.rlim_max;
	setrlimit(RLIMIT_NOFILE, &limit);

	printf("set socket open fd max count to %d\n", limit.rlim_max);
}


